A SMART building that monitors the movements of people inside it sounds like a way for your boss to spy on you. In fact, a building with a network of motion detectors can improve the energy efficiency and safety of the building while remaining deaf and blind to the activities of individuals.
Such systems could use their knowledge of where groups congregate to turn down the air conditioning when there are only a few people in one part of the building, for example. In an emergency, electronic signs could direct people to the nearest available escape route when one becomes congested.
Rather than using cameras, which would invade people's privacy, Christopher Wren at the Mitsubishi Electric Research Laboratory (MERL) in Cambridge, Massachusetts, is using "dumb" infrared motion sensors similar to those used to control automatic lights.
"Imagine peeling the roof off the building and watching people go about their lives, like in an ant farm," he says. "You can't identify individual ants or keep track of them as they scurry past each other, but you can watch as they move food into the nest or dig chambers."
"Imagine peeling the roof off and watching people go about their lives, like in an ant farm
Wren fitted 215 wireless sensors to the ceilings of two floors of the MERL building and collected information from them over the course of a year. He also installed video cameras so he could match up the signals from the motion sensors with what movements were actually taking place, such as walking in a straight line, loitering, or people walking together or splitting apart.
He used his findings to program software to learn how signal patterns corresponded to different movements. When the software was then fed new motion data, it was able to accurately identify the movements 91 per cent of the time.
Wren has also programmed the software to detect patterns of movement that correspond to activities such as meetings. He has also programmed it to combine motion signals with information from other sources such as printer logs, to demonstrate that it can detect more complex actions like people collecting files from the printer.
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